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from authlib.common.encoding import (
to_bytes,
to_unicode,
urlsafe_b64encode,
json_b64encode,
)
from authlib.jose.util import (
extract_header,
extract_segment, ensure_dict,
)
from authlib.jose.errors import (
DecodeError,
MissingAlgorithmError,
UnsupportedAlgorithmError,
BadSignatureError,
InvalidHeaderParameterNameError,
)
from .models import JWSHeader, JWSObject
class JsonWebSignature:
#: Registered Header Parameter Names defined by Section 4.1
REGISTERED_HEADER_PARAMETER_NAMES = frozenset([
'alg', 'jku', 'jwk', 'kid',
'x5u', 'x5c', 'x5t', 'x5t#S256',
'typ', 'cty', 'crit'
])
#: Defined available JWS algorithms in the registry
ALGORITHMS_REGISTRY = {}
def __init__(self, algorithms=None, private_headers=None):
self._private_headers = private_headers
self._algorithms = algorithms
@classmethod
def register_algorithm(cls, algorithm):
if not algorithm or algorithm.algorithm_type != 'JWS':
raise ValueError(
f'Invalid algorithm for JWS, {algorithm!r}')
cls.ALGORITHMS_REGISTRY[algorithm.name] = algorithm
def serialize_compact(self, protected, payload, key):
"""Generate a JWS Compact Serialization. The JWS Compact Serialization
represents digitally signed or MACed content as a compact, URL-safe
string, per `Section 7.1`_.
.. code-block:: text
BASE64URL(UTF8(JWS Protected Header)) || '.' ||
BASE64URL(JWS Payload) || '.' ||
BASE64URL(JWS Signature)
:param protected: A dict of protected header
:param payload: A bytes/string of payload
:param key: Private key used to generate signature
:return: byte
"""
jws_header = JWSHeader(protected, None)
self._validate_private_headers(protected)
algorithm, key = self._prepare_algorithm_key(protected, payload, key)
protected_segment = json_b64encode(jws_header.protected)
payload_segment = urlsafe_b64encode(to_bytes(payload))
# calculate signature
signing_input = b'.'.join([protected_segment, payload_segment])
signature = urlsafe_b64encode(algorithm.sign(signing_input, key))
return b'.'.join([protected_segment, payload_segment, signature])
def deserialize_compact(self, s, key, decode=None):
"""Exact JWS Compact Serialization, and validate with the given key.
If key is not provided, the returned dict will contain the signature,
and signing input values. Via `Section 7.1`_.
:param s: text of JWS Compact Serialization
:param key: key used to verify the signature
:param decode: a function to decode payload data
:return: JWSObject
:raise: BadSignatureError
.. _`Section 7.1`: https://tools.ietf.org/html/rfc7515#section-7.1
"""
try:
s = to_bytes(s)
signing_input, signature_segment = s.rsplit(b'.', 1)
protected_segment, payload_segment = signing_input.split(b'.', 1)
except ValueError:
raise DecodeError('Not enough segments')
protected = _extract_header(protected_segment)
jws_header = JWSHeader(protected, None)
payload = _extract_payload(payload_segment)
if decode:
payload = decode(payload)
signature = _extract_signature(signature_segment)
rv = JWSObject(jws_header, payload, 'compact')
algorithm, key = self._prepare_algorithm_key(jws_header, payload, key)
if algorithm.verify(signing_input, signature, key):
return rv
raise BadSignatureError(rv)
def serialize_json(self, header_obj, payload, key):
"""Generate a JWS JSON Serialization. The JWS JSON Serialization
represents digitally signed or MACed content as a JSON object,
per `Section 7.2`_.
:param header_obj: A dict/list of header
:param payload: A string/dict of payload
:param key: Private key used to generate signature
:return: JWSObject
Example ``header_obj`` of JWS JSON Serialization::
{
"protected: {"alg": "HS256"},
"header": {"kid": "jose"}
}
Pass a dict to generate flattened JSON Serialization, pass a list of
header dict to generate standard JSON Serialization.
"""
payload_segment = json_b64encode(payload)
def _sign(jws_header):
self._validate_private_headers(jws_header)
_alg, _key = self._prepare_algorithm_key(jws_header, payload, key)
protected_segment = json_b64encode(jws_header.protected)
signing_input = b'.'.join([protected_segment, payload_segment])
signature = urlsafe_b64encode(_alg.sign(signing_input, _key))
rv = {
'protected': to_unicode(protected_segment),
'signature': to_unicode(signature)
}
if jws_header.header is not None:
rv['header'] = jws_header.header
return rv
if isinstance(header_obj, dict):
data = _sign(JWSHeader.from_dict(header_obj))
data['payload'] = to_unicode(payload_segment)
return data
signatures = [_sign(JWSHeader.from_dict(h)) for h in header_obj]
return {
'payload': to_unicode(payload_segment),
'signatures': signatures
}
def deserialize_json(self, obj, key, decode=None):
"""Exact JWS JSON Serialization, and validate with the given key.
If key is not provided, it will return a dict without signature
verification. Header will still be validated. Via `Section 7.2`_.
:param obj: text of JWS JSON Serialization
:param key: key used to verify the signature
:param decode: a function to decode payload data
:return: JWSObject
:raise: BadSignatureError
.. _`Section 7.2`: https://tools.ietf.org/html/rfc7515#section-7.2
"""
obj = ensure_dict(obj, 'JWS')
payload_segment = obj.get('payload')
if payload_segment is None:
raise DecodeError('Missing "payload" value')
payload_segment = to_bytes(payload_segment)
payload = _extract_payload(payload_segment)
if decode:
payload = decode(payload)
if 'signatures' not in obj:
# flattened JSON JWS
jws_header, valid = self._validate_json_jws(
payload_segment, payload, obj, key)
rv = JWSObject(jws_header, payload, 'flat')
if valid:
return rv
raise BadSignatureError(rv)
headers = []
is_valid = True
for header_obj in obj['signatures']:
jws_header, valid = self._validate_json_jws(
payload_segment, payload, header_obj, key)
headers.append(jws_header)
if not valid:
is_valid = False
rv = JWSObject(headers, payload, 'json')
if is_valid:
return rv
raise BadSignatureError(rv)
def serialize(self, header, payload, key):
"""Generate a JWS Serialization. It will automatically generate a
Compact or JSON Serialization depending on the given header. If a
header is in a JSON header format, it will call
:meth:`serialize_json`, otherwise it will call
:meth:`serialize_compact`.
:param header: A dict/list of header
:param payload: A string/dict of payload
:param key: Private key used to generate signature
:return: byte/dict
"""
if isinstance(header, (list, tuple)):
return self.serialize_json(header, payload, key)
if 'protected' in header:
return self.serialize_json(header, payload, key)
return self.serialize_compact(header, payload, key)
def deserialize(self, s, key, decode=None):
"""Deserialize JWS Serialization, both compact and JSON format.
It will automatically deserialize depending on the given JWS.
:param s: text of JWS Compact/JSON Serialization
:param key: key used to verify the signature
:param decode: a function to decode payload data
:return: dict
:raise: BadSignatureError
If key is not provided, it will still deserialize the serialization
without verification.
"""
if isinstance(s, dict):
return self.deserialize_json(s, key, decode)
s = to_bytes(s)
if s.startswith(b'{') and s.endswith(b'}'):
return self.deserialize_json(s, key, decode)
return self.deserialize_compact(s, key, decode)
def _prepare_algorithm_key(self, header, payload, key):
if 'alg' not in header:
raise MissingAlgorithmError()
alg = header['alg']
if self._algorithms is not None and alg not in self._algorithms:
raise UnsupportedAlgorithmError()
if alg not in self.ALGORITHMS_REGISTRY:
raise UnsupportedAlgorithmError()
algorithm = self.ALGORITHMS_REGISTRY[alg]
if callable(key):
key = key(header, payload)
elif key is None and 'jwk' in header:
key = header['jwk']
key = algorithm.prepare_key(key)
return algorithm, key
def _validate_private_headers(self, header):
# only validate private headers when developers set
# private headers explicitly
if self._private_headers is not None:
names = self.REGISTERED_HEADER_PARAMETER_NAMES.copy()
names = names.union(self._private_headers)
for k in header:
if k not in names:
raise InvalidHeaderParameterNameError(k)
def _validate_json_jws(self, payload_segment, payload, header_obj, key):
protected_segment = header_obj.get('protected')
if not protected_segment:
raise DecodeError('Missing "protected" value')
signature_segment = header_obj.get('signature')
if not signature_segment:
raise DecodeError('Missing "signature" value')
protected_segment = to_bytes(protected_segment)
protected = _extract_header(protected_segment)
header = header_obj.get('header')
if header and not isinstance(header, dict):
raise DecodeError('Invalid "header" value')
jws_header = JWSHeader(protected, header)
algorithm, key = self._prepare_algorithm_key(jws_header, payload, key)
signing_input = b'.'.join([protected_segment, payload_segment])
signature = _extract_signature(to_bytes(signature_segment))
if algorithm.verify(signing_input, signature, key):
return jws_header, True
return jws_header, False
def _extract_header(header_segment):
return extract_header(header_segment, DecodeError)
def _extract_signature(signature_segment):
return extract_segment(signature_segment, DecodeError, 'signature')
def _extract_payload(payload_segment):
return extract_segment(payload_segment, DecodeError, 'payload')